Types of sieves
According to the screening media the sieves are divided into three groups:
Sieves with metallic mesh
The metallic mesh is soldered to a frame. This is the classic type of sieve. Generally it is identified by the nominal opening (in mm., if the opening is equal to or above 1.0mm., or in µ when it is below). It may also be identified with the term “Mesh” which indicates the number of openings per English Inch (1” = 25.4mm.). To find the equivalence to the nominal aperture it is necessary to consult the ASTM E-11 standard, which shows the exact size.
Sieves with perforated plates
The metallic perforated plate has either square, round, or rectangular holes, and the plate is soldered to a frame. Normally this type of sieve is used when the holes are 4.00mm. or above.
Sieves with electroformed plates
The plate of this type of sieve is usually made of nickel which has gone through a chemical erosion process. The range of apertures is from 2.00mm. to 5µ.
The principal characteristic of this sieve is its high precision; the inconvenience is the price.